stat is a function provided by the operating system.  As such, the
results of stat are not guaranteed to be the same from one operating
system to another.  You have to find documentation for your own system
to ensure you have the proper meaning for your system.

However, it is expected that stat, along with lstate and fstat, are
functions relating to information about a particular file.  Typically
stat takes an argument of a file name, and fstat takes an argument of
an open file descriptor.  lstat is a bit different - while it takes an
argument of a file name, if the file name is some sort of aliases or
symbolic representation of another file, that other file's stat information
is what is returned.